Fluid pressure switch



Oct, 13, 1953 A. N. szwARGULsKl ET AL 2,655,573

FLUID PRESSURE SWITCH Filed Jan. 15 1951 FIG.

FIG.5.

FIG.7.-

INVENTOR.

ALEX N. SZWARGULSKI R. LAR

SON

QJ/w ATTORNEY Patented c't. 13, 1953 FLUID PRESSURE SWITCH Alex N. Szwargulski, St. Louis, and Paul R. Larson, Pine Lawn, Mo., assignors to Carter Carburetor Corporation, St. Louis, poration of Delaware Mo., a cor- Application January 15, 1951, Serial No. 206,087

4 Claims.

This invention relates to fluid pressure actuated switches for electrical circuits.

The object of the invention is to provide a novel, simplied, inexpensive, rugged, and sensitive electrical switch which is actuated in response to a change in fluid pressure applied thereto.

This object and other more detailed objects hereafter appearing are attained by the device villustrated in the accompanying drawing in which:

Fig. 1 is a top View of the novel switch.

Fig. 2 is a vertical, transverse section through 'the switch.

Fig. 3 is a similar section, but showing the :switch opened.

Fig. 4 is a top view of the adjustable plunger head disassembled.

Fig. 5 is a side View of the plunger head.

Fig. 6 shows a modified form of sealing grommet for the switch casing.

Fig. 7 is a detail section showing another modification.

The switch is mounted within a casing having a cylindrical side wall 8, a top wall 9, and a bottom wall I0 which includes a threaded tting II for connection to a source of uid pressure a change in which is to be sensed. The inner surface of wall I0 around fitting II is planar and a diaphragm I2 of suitable, flexible material, such as synthetic rubber, rests upon this surface and is secured thereto by the lower edge flange I3 of a cup-shaped member I4 received within the casing. The lower edge portion of casing wall 8 is annularly recessed, as at I 5, to receive and clamp together wall I0, the diaphragm, and flange I3, to sealingly maintain the assembly. Casing wall 8 has an outward depression I8 which receives a lug I'I on the cup-shaped member to insure and maintain accurate assembly thereof.

Telescopingly received within cup member I 4 is an opposing cup which rests centrally upon diaphragm I2. A plunger shank 2I projects from the center of cup 20 and has a reduced, threaded portion 22 upon which is secured a head element 23 of plastic or other non-conducting material. This head element is non-circular, as shown in Fig. 4, and is slidably and non-rotatably received in a recess 24 formed in the base or top wall of ,member I4. A coiled spring 25 is compressed between member UI and cup 20 and urges the cup into frictional engagement with the diaphragm and urges the diaphragm in opposition to the force of pressure applied through tting II.

An insulating gasket 26 is secured to the undersurface of top wall 9 of the main casing and a spring strip 2'I of general U contour has an eX- tended base 21a secured by means of spaced rivets 28 which also secure a clip 29, with a terminal screw 30, to the top of the casing. Another insulating gasket 3I is interposed between the top of the casing and the clip. The free extremity of spring strip 21 carries a movable switch contact 32 in operative relationship with a stationary switch contact 33 mounted in the top of member I 4. A kerf 34 is formed in the top of threaded plunger extension 22 for reception of a screw driver to adjust the plunger. The screw driver is introduced through an opening 35 in the casing top, normally sealed by an expansible cup element 35, and an aperture 31 in spring strip carrier 2l. Certain features here shown are covered in a Patent No. 2,537,354 in the names of Korte and Szwargulski.

During normal operation, the frictional engagement between cup 20 and the diaphragm, induced by main switch spring 25, effectively resists unauthorized rotation of switch actuating plunger 2I and consequently, maintains the desired adjustment. On the other hand, adjustment may be efected, if desired, by the application of a screw driver to the plunger eXtension. Another important feature of the invention is the normal planar disposition of diaphragm I2 whereby its movements are restricted to one side of dead center namely, upward, and, accordingly, the diaphragm does not pass over center. It has been found that over center motion of the diaphragm results in erratic switch action.

The switch, which is normally closed, as in Fig. 2, may control a circuit for an indicator, such as an electric lamp. Under all normal running conditions of the engine, when the lubrication system is in proper order, the diaphragm will be urged upwardly, as in Fig. 3, opening the switch contacts. However, in case of failure in the lubricating system, these contacts will close, completing the indicator circuit so that the operator will be apprised of the failure before damage can result.

Figs. 6 and 7 show modified seals for the adjustment opening in the top of the casing. In Fig. 6, a rubber grommet 40 is inserted in opening 35 in place of the metal cup 36. In Fig. 7 clip 29 is eliminated and terminal screw 30a, itself, closes the adjustment opening. Rivets 28a secure together switch spring arm base 21a, gasket 26a, casing top wall 9a, gasket 3Ia of phenolic condensate or similar plastic material,

and a retainer plate 29a. Gasket Sla is originally provided with a central cylindrical holer somewhat smaller than the diameter of the terminal screw thread. The screw, then, cuts its own threads in the gasket to insure a moisture and dust proof nt.

The invention 'may be modiedfin various de'- tails as will occur to those -skilled lin the .art and the exclusive use of all modications as come within the scope of the appended claims is contemplated.

We claim:

l. In a luid pressure switch, iiui'd pressure connection having a surrounding wall, a flexible diaphragm clamped against said wall, a movable and a stationary switch contact on the opposite side of said diaphragm from said connection, a carrier for said movable Contact, a member rigidly supported between said diaphragm fand isa-id movable switch contactiand having a guide relcess, said .stationary Acontact being mounted 'en said member., 'a switch actuating plunger 1 extending froms'aid diaphragm tothe proximity of said Iswitch Vcontact carrier, rsaid plunger including "Shank and .head parts -thre'adedly connected for freiative adjustment, 'one of ssaid'partsbeing slidlably Vreceived insaid gui-de y.recess to resist unauthcrize'd rotation thereof, and va'spring 'stressed between said member and said plunger .for urging the latter Tandfsaiddiaphragm/in Aopposition to the iuid .pressure applied through said Yiconnection, 1 saidfplunger valso #including la Aspringseat `'elemer'i't rig-id lftherfewitlfi fand :interposed between said spring Tand-said diaphragi'n vvvl-i'e'reby said fs'prling frictional'ly iin-'ges 'fsaii'd Vvplunger against said 'diaphragm-#toiresist relative turning thereof.

"2. A nuid pressure -Aoperatedswitch'comprising Aa "casing 'with `one waltarranged for connection to a nuid pressure line, saidwall having iap'l'a'nar,

Von the periphery'iofl'sa-i diaphragm land :securing "the same to' said *ii/fail, `said A`-irlemb'er .having v.a `Ycentral recess, vsta lpoints "mounted-within# said easing, a shitable nary and movable switeh 'elementcarryingfsaid movable po'intland extending ladjacent the -base l--po'rftion-of lsaidlrrierr-iber,

a Aplunger projecting fthroughs'ai'd base por-tion,

said plunger vlin'ciiiding a foot element resting VVagainst said diaphragm, an lactuator y-heads'lidlably and non-rotatably received lin Asaid recess andv ac'i'apte'dY to' move fsaid Vsh'if't'ablei element upon adjusting said `head and vthe zfricti'o'nal Yengage-.- 'ment between 'said -foo't element and said diaphraglrn' resisting unauthorizedturning of said shank part.

'53, In `a liiiiid pressureswitchfaiiuid pressure connection having 4 a surrounding wall;a"1iexible diaphragm clamped-against isaid wall; a movable 4 and a stationary switch contact on the opposite side of said diaphragm from said connection, a carrier for said movable contact, a member rigidly supported between said diaphragm and said movable switch conta-ct and having a guide recess, said stationary Contact being mounted -on said member, a switch actuating plunger extendling from said diaphragm to the proximity of said switch contact carrier, said plunger includling shank and head parts threadedly connected for relative adjustment, one of said parts being s'li'da'bl'y received in said guide recess to resist unauthorized rotation thereof, and a spring stressed l:between :said member and said plunger `for urging the latter and said diaphragm in yopposition to the pressure applied through said connection, said plunger also including a spring seat element rigid 'therewith and interposed between `said spring and said diaphragm whereby said spring urges said plunger against said diaphragm, saidpiungerhaving a-portion ier accommodating a turning ftoolpresented outwardly for adjusting said plunger, the frictional engagement between said diaphragm and `said seat .element .resisting unauthorized turning of saidp-lunger.

4. In a iiuid pressure ,-switchfa uid pressure connection having a surrounding wall, aiiexible `diaphragm clamped against saidwall, .a .movable :and ia stationaryswitch Contact .on the apposite side fof said diaphragm from said Yconnection, a carrier for said movable contact, a memberI rigidly supp ortedv .between said diaphragm and said-.mov- .ab'le switch contact-and havinga guide recess, said stationary contact being mounted aon-said member, a `switch actuating j plunger extending from said diaphragm to the proximity of A said switch Contact carrier, said plunger `incli-id-ing shank and head parts threadedly v1cen-nected ,ier relative adjustment, .one fofsaid parts ming. slid- .ably received in said guide recess Lto resist unauthorized rotation thereofmanda-spring stressed betweenfsaid member-.and said plungerior the latter and said diaphragm in opposit-,imito fthe .-iiuid pressure .applied through` said `:connection, said plunger including a spring .seat element rigid therewith and .interposed ibetween Said switch vaction-and the frictional engagementbetween said idiaphragm and V,said -seat :element ...resisting f .runauthorizedrturning of .said =plunger..

ALEX SZWARGHLSKL '55 :PAUL FR. LARSQN,

References Cited .inthe ,'ille .-ofV this A,patent UNITED VSi" fA"-I`ES PATENTS 'Number "Name .Date

1,555,419 lif/rammel ei ai. sept.-29,1192'5 2,069,222 Cremer "Fe'b: 2,"1937 "2;1i 97;0'25 Clason Feb;`7119'5() 1375889 fFrance Fed-,4,1931

' '(Zd addition vto No: 656,557) 

